1. Field of the Invention
The present invention relates to technologies for measuring dimensional errors of a cylinder of an object to be integrally rotated about a rotation axis, the cylinder being eccentric with the rotation axis as planned or not.
2. Discussion of the Related Art
Conventionally, grinding a workpiece such as a crankpin of a crankshaft used in a gasoline engine, or a cam, is effected by precisely synchronizing a rotary motion of the workpiece about a rotation axis (referred to as the xe2x80x9cC-axisxe2x80x9d where appropriate), and a linear motion of a tool stand such as a grindstone stand in a direction (referred to as the xe2x80x9cX-axis directionxe2x80x9d) perpendicular to the C-axis.
In the conventional art, by virtue of an advanced technology in the field associated with devices such as a servo-control device or a numerical control device, accuracies in the follow-up control, the synchronization or the movement of a machine has been improved.
However, it is the fact that only the improved accuracies in those areas above-mentioned, cannot adequately eliminate a profile error of a workpiece due to a change in rigidity of the workpiece, a change in a grinding force acting on the workpiece, and the like. Therefore, for a high precision in grinding, it is traditional that a workpiece is removed from a grinding machine before completion of a grinding process for the workpiece, and then geometrical errors of the workpiece (e.g., a circularity deviation of a crankpin and a profile of a cam) is measured. The measurements are used to obtain an amount of compensation for motion of the workpiece in a direction of the C- or X-axis, and subsequently the grinding for the same workpiece is initiated again under the new machining condition compensated accordingly.
In the field of measurement technology, there is generally well known a method employing a three-point contact type described in a technical paper titled xe2x80x9cMETHOD FOR MEASURING CIRCULARITY DEVIATION OF CYLINDRICAL WORKPIECExe2x80x9d (Japan Mechanical Engineering Association, Vol. 53, No. 376, May 1950), for example, as a method for accurately measuring a circularity deviation of a cylindrical workpiece. This technical paper explains a theoretical analysis for a case where a circularity deviation of a cylindrical workpiece is measured using a measuring device of a three-point contact method including a V-block type, a riding gauge type (wherein the V-shaped gauge is used so as to ride on the cylindrical workpiece) and a three-armed type. The paper teaches a method for quantitively obtaining an error of a cylindrical workpiece from a geometrically true circle in the manner shown by the following equations (1)-(6) and in FIGS. 14-16 in the case of the riding type, by way of example.
Variables, symbols, functions, etc. which will be used for explanation of the content of the technical paper, are defined as followed:
(Figure Symbols)
K: cylindrical workpiece such as a crankpin (i.e., a circumference of a cross sectional profile of the workpiece)
O: original point (i.e., one arbitrary point near the center of the circumference xe2x80x9cKxe2x80x9d: a fixed point on the cross section of the workpiece)
C: arbitrary and stationary point defining an original line OC on a cross section of the workpiece)
M: gauge cylinder with a standard dimension of a radius am (i.e., a circumference of a cross section of the gauge cylinder)
a: point of contact of an end face of a measuring head of the measuring device of the three-point contact type (i.e., the riding gauge type) with the circumference xe2x80x9cKxe2x80x9d
b: one of two contact points at which two contact surfaces of the riding gauge contact the circumference xe2x80x9cKxe2x80x9d
c: the other of the two contact points mentioned above
d: reference or datum point of the riding gauge (i.e., a center point of an opposing angle xcex1 mentioned below)
axe2x80x2: foot of perpendicular pendent from the original point O to an end face of the measuring head of the measuring device
bxe2x80x2: foot of perpendicular pendent from the original point O to one of the two contact surfaces of the riding gauge
cxe2x80x2: foot of perpendicular pendent from the original point O to the other of the two contact surfaces of the riding gauge
(Variables)
xcex8: angle relative to the original line OC
xcex1: opposing angle between the two contact surfaces of the riding gauge which are opposed to each other not in parallel
n: natural number (i.e., an index of the expansion of the Fourier series)
(Constants)
a0: average radius of circumferences xe2x80x9cKxe2x80x9d
cn: expansion coefficient of each term of the Fourier series for a radius r(xcex8) as mentioned below, when the expansion thereof is performed (obtained by the harmonic analysis)
xcfx86n: initial phase of each term of the Fourier series for the radius r(xcex8) when the expansion thereof is performed (obtained by a harmonic analysis)
am: radius of the gauge cylinder xe2x80x9cMxe2x80x9d
my: average of outputs y(xcex8) of the measuring device, as mentioned below
J: upper limit of the natural number n mentioned above (practically, xe2x80x9cJxe2x80x9d is enough when adopts about xe2x80x9c50.xe2x80x9d In the technical paper mentioned above, the principle consideration is taken up to when J=12.).
N: the number of measuring times which the outputs y(xcex8) are actually measured (i.e., the sampling number of the measuring points)
(Functions)
r(xcex8): function for a radius of the circumference xe2x80x9cKxe2x80x9d, and of the angle xcex8 as an independent variable of the function
y(xcex8): function for an output of the measuring device of the three-point contact type, and of the angle xcex8 as an independent variable of the function
xcexc(xcex1,n): function for a magnification of each component of a spectrum shown in the output y(xcex8), which magnification serves to magnify a value of the term xe2x80x9ccn cos(nxcex8+xcfx86n) xe2x80x9d in the equation (3) mentioned below
r(xcex8)=a0+n=1xcexa3Jcn cos(nxcex8+xcfx86nxe2x80x83xe2x80x83(1)
am{1/sin(xcex1/2)xe2x88x921}xe2x88x92y(xcex8)={r(xcex8+xcfx80/2xe2x88x92xcex1/2)+r(xcex8xe2x88x92xcfx80/2+xcex1/2)}/{2 sin(xcex1/2)}xe2x88x92r(xcex8)xe2x80x83xe2x80x83(2)
y(xcex8)=(a0xe2x88x92am)xc2x7{1xe2x88x921/sin(xcex1/2)}+n=2xcexa3J{xcexc(xcex1, n) cn cos(nxcex8+xcfx86n)}xe2x80x83xe2x80x83(3)
xcexc(xcex1, n)=1xe2x88x92{cos n(xcfx80/2xe2x88x92xcex1/2)}/sin(xcex1/2)xe2x80x83xe2x80x83(4)
                                          m            y                    =                      ∫                                          y                ⁡                                  (                  θ                  )                                            ⁢                                                ⅆ                  θ                                /                2                            ⁢                              xe2x80x83                            ⁢              π              ⁢                              xe2x80x83                            ⁢                              (                                                      interval                    ⁢                                          xe2x80x83                                        ⁢                    of                    ⁢                                          xe2x80x83                                        ⁢                    integral                    ⁢                                          :                                        ⁢                                          xe2x80x83                                        ⁢                    0                                    ≦                  θ                  ≦                                      2                    ⁢                                          xe2x80x83                                        ⁢                    π                                                  )                                                                                  =                                    (                                                a                  0                                -                                  a                  m                                            )                        ·                          {                              1                -                                                      1                    /                    sin                                    ⁢                                      xe2x80x83                                    ⁢                                      (                                          α                      /                      2                                        )                                                              }                                            ⁢                              =                                    (                                                ∑                                      i                    =                    0                                                        N                    -                    1                                                  ⁢                                  y                  i                                            )                        /            N                                                (          5          )                                                          a            0                    =                                    a              m                        +                                          m                y                            /                              {                                  1                  -                                      1                    /                                          sin                      ⁡                                              (                                                  α                          /                          2                                                )                                                                                            }                                                                          (          6          )                    xe2x80x83a0=am+my/{1xe2x88x921/sin(xcex1/2)}xe2x80x83xe2x80x83(6)
The expansion coefficients c, and initial phases xcfx86n for all the natural numbers n can be calculated when the outputs y(xcex8) are measured using a suitable opposing angle xcex1 or a suitable combination of opposing angles xcex1 in the three-point contact method. Therefore, it will be understood from the technical paper mentioned above that an error in profile of the actual cylinder K from a geometrically true circle (represented by the gauge cylinder xe2x80x9cMxe2x80x9d) can be quantitively obtained as xe2x80x9cxcex4r=r(xcex8)xe2x88x92am according to the above equation (1). Wherein, the gauge cylinder xe2x80x9cMxe2x80x9d with a standard dimension of the radius am is a desired cylinder.
It is noted that those definitions of variables, symbols, functions, etc. will be applicable to the following explanation.
The conventional technology mentioned above suffers from the following problems, and therefore, a general improvement in the art has been expected:
(Problem 1)
In a case where a workpiece is removed from a grinding machine before completion of a grinding process thereby, and where an accurate measurement of a profile of the workpiece (e.g., a circularity deviation of a cylinder of the workpiece) is then performed, there may arise a positional deviation between reference points set on the grinding machine and a measuring device for measuring the profile of the ground workpiece, respectively. Consequently, the positional deviation causes an inadequate degree of measuring accuracy of the workpiece, in many cases.
(Problem 2)
A process of setting the reference point for measurement of the workpiece, as mentioned above, requires a long time for adjusting the measuring condition, and the setting process is difficult to be automatized. As a result, productivity in a machining process such as a cylindrical grinding one fails to improve.
(Problem 3)
According to our proposal, there exists a case where an eccentric cylinder such as a crankpin aforementioned, which is a part of a workpiece, is scanned by a measuring device of a three-point contact type, with the workpiece still held rotatably by a machine, for measurement of a circularity deviation of the eccentric cylinder. In this case, the machine may be a grinding one in which a rotation of the workpiece about the C-axis and a feeding operation of a tool stand for a grindstone are synchronized with each other. In the proposed technology, the measuring device is attached to the grinding machine by a motion controlling mechanism for controlling a mechanical motion of the measuring device relative to the grinding machine, which mechanism is mainly constructed by a link mechanism. The measuring device is required to be moved along a circumference of the eccentric cylinder in contact with the circumference.
However, in this arrangement, freedom in motion of the link mentioned above is high. In addition, this arrangement is constructed to have a system of measurement in which the feeding operation of the tool stand, a change in attitude of the motion controlling mechanism, the measuring device, and the rotation of the eccentric cylinder about the C-axis are related to one another. As a result, the system of measurement also has freedom in motion thereof in directions of the C and X axes.
For the above reasons, it is not easy to accurately measure a phase angle (i.e., the aforementioned angle xcex8) of the eccentric cylinder about its center, concurrently with the measurement of the circularity deviation (i.e., the aforementioned output y(xcex8)).
There is a case where a crankshaft used in an engine having a plurality of cylinders is manufactured, for instance. In this case, unless the crankshaft is manufactured such that each of a plurality of crankpins thereof is accurate in position (i.e., an amount of eccentricity of each crankpin, and a phase of each crankpin about the rotating axis of the crankshaft) relative to a crank journal of the crankshaft, characteristics of the engine such as a compression ratio of a gas to be ignited and an ignition phase (i.e., ignition timing) can not be accurately obtained for each cylinder of the engine. Therefore, it is necessary to develop an apparatus for quickly and accurately measuring a position of an axis of an eccentric cylinder such as one of the crankpins, in order to efficiently manufacture a number of engines which are so high in performance as to adequately eliminate fuel consumption, vibration, noise, and the like.
The extremely accurate measurement of a position of an axis of an eccentric cylinder is adequately useful in measuring a circularity deviation of an eccentric cylinder, as well. Therefore, development .of means for quickly and accurately measuring the position of the axis of the eccentric cylinder has been expected.
It is therefore a first object of the present invention to provide an apparatus for accurately and quickly measuring a circularity deviation of an eccentric cylinder having eccentricity as intended or not.
It is a second object of the present invention to provide an apparatus for machining an eccentric cylinder having eccentricity as intended or not, with an improved circularity of the eccentric cylinder and in a reduced time.
It is a third object of the present invention to provide an apparatus for accurately and quickly measuring a position of a center of an eccentric cylinder having eccentricity as intended or not.
It is a fourth object of the present invention to provide an apparatus for machining an eccentric cylinder having eccentricity as intended or not, with an improved accuracy of a position of a center of the eccentric cylinder and in a reduced time.
It is a fifth object of the present invention to provide an apparatus for machining an eccentric cylinder having eccentricity as intended or not, with an improved circularity of the eccentric cylinder and an improved accuracy of a position of a center of the eccentric cylinder, and in a reduced time.
These objects indicated above may be achieved according to any one of the following modes of this invention. Each of these modes of the invention is numbered like the appended claims, and depends from the other mode or modes, where appropriate. This type of explanation about the present invention is for better understanding of some ones of a plurality of technical features and a plurality of combinations thereof disclosed in this specification, and dose not mean that the plurality of technical features and the plurality of combinations in this specification are interpreted to encompass only the following modes of this invention:
(1) An apparatus for measuring a circularity deviation of a cylinder of an object intended to be integrally rotated about a rotation axis, the cylinder being eccentric as either intended or not with the rotation axis, the apparatus comprising:
a first measuring device measuring a circumferential surface of the cylinder at each measuring point xe2x80x9cpxe2x80x9d thereon in a three-point contact method;
a motion controlling mechanism permitting the first measuring device to be moved along a circumference of the cylinder, which circumference lays on a cross section of the cylinder perpendicular to the rotation axis, in contact with the circumferential surface of the cylinder, during rotation of the cylinder about the rotation axis;
a circularity deviation calculating device calculating the circularity deviation of the cylinder, on the basis of a relative position xe2x80x9cxxe2x80x9d of the rotation axis relative to the apparatus for measuring the circularity deviation, a rotating angle xcfx86 of the cylinder about the rotation axis, and an output xe2x80x9cyxe2x80x9d of the first measuring device.
The apparatus according to this mode (1) would achieve the first object of the present invention mentioned above, which is to say, to provide an apparatus for accurately and quickly measuring a circularity deviation of an eccentric cylinder having eccentricity as intended or not.
In the apparatus according to this mode (1) the term xe2x80x9crotation axisxe2x80x9d may be interpreted to mean an axis about which the cylinder is rotatable continuously in one direction, or mean an axis about which the cylinder is rotatable alternately in opposite directions. The selection of the definitions about the term xe2x80x9crotation axisxe2x80x9d would not affect the operation and results of the apparatus according to this mode (1), as mentioned above. It is noted that this interpretation about the term xe2x80x9crotation axisxe2x80x9d is applicable to the following modes.
In the apparatus according to this mode (1), the relative position xe2x80x9cxxe2x80x9d, rotating angle xcfx86, and output xe2x80x9cyxe2x80x9d which are to be used for calculating the circularity deviation for each angle xcex8 (e.g., each measuring point xe2x80x9cpxe2x80x9d) of the cylinder may be related to one another in that they are established together with relation to each angle xcex8.
(2) The apparatus according to the above mode (1), wherein the object is a workpiece, a circumferential surface of which is machined by a machine contacting a tool attached to a tool stand of the machine, with the circumferential surface of the workpiece for machining, the measurement of the circularity deviation by the apparatus for measuring the circularity deviation is performed without removal of the workpiece from the machine.
In the apparatus according to this mode (2), a circularity deviation of an eccentric cylinder formed integrally on a workpiece, which is held rotatably about a rotation axis within a machine such as a grinding machine, can be measured without removal of the workpiece out of the machine. In other words, it is unnecessary to remove the workpiece out, during the measurement of the circularity deviation of the eccentric cylinder. As a result, the apparatus according to this mode (2) would leave out a removing and installing process of a workpiece from and on a machine for the measurement, and at the same time, would not arise a deviation of a set position of the workpiece between during machining process and during measuring of the circularity deviation. For this reason, a circularity deviation of an eccentric cylinder can be measured in a reduced time.
(3) The apparatus according to the above mode (2), wherein the machine moves the cylinder and the tool stand relatively to each other in a feeding direction perpendicular to the rotation axis, thereby permitting the tool to follow the cylinder during rotation of the cylinder about the rotation axis, resulting in a change in the relative position xe2x80x9cxxe2x80x9d.
(4) The apparatus according to any one of the above modes (1)-(3), wherein the circularity deviation calculating device comprises:
a second measuring device measuring the relative position xe2x80x9cxxe2x80x9d;
a third measuring device measuring the rotating angle xcfx86; and
circularity deviation calculating means calculating the circularity deviation, on the basis of the measured relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86, and the output xe2x80x9cyxe2x80x9d of the first measuring device.
(5) The apparatus according to any one of the above modes (1)-(4), wherein the motion controlling mechanism is adapted to have a geometrical configuration permitting a relationship among the relative position xe2x80x9cxxe2x80x9d, the rotating angle xcfx86, and an angle xcex8 of the cylinder about an original point O defined to be located at or near a center of the cylinder, to be independent of a change in an attitude of the motion controlling mechanism, which attitude results from rotation of the cylinder.
(6) The apparatus according to the above mode (5), wherein the motion controlling mechanism comprises:
a first arm coupled with an stationary member, pivotable about a first pivoting axis offset in parallel from the rotation axis;
a second arm coupled with a free end of the first arm, pivotable about a second pivoting axis offset in parallel from the rotation axis, the second arm carrying at a free end thereof the first measuring device.
(7) The apparatus according to the above mode (6), wherein the second arm is configured to have a first sub-arm extending from the second pivoting axis, and a second sub-arm secured to the first sub-arm so as to form a predetermined fixed angle xcex6 therebetween, the second sub-arm carrying at a free end thereof the first measuring device.
(8) The apparatus according to any one of the above modes (1)-(7), wherein the circularity deviation calculating device comprises first variable-transforming means expressing a position of the each measuring point xe2x80x9cpxe2x80x9d on the circumferential surface of the cylinder, according to a system of 2-dimensional polar coordinates formulated on a coordinate plane which is defined by an original point O predetermined to be located at or near a center of the circumference of the cylinder, and an original line OC predetermined to extend from the original point O and which is fixed to the circumference of the cylinder, using a distance xe2x80x9crxe2x80x9d from the original point O and an angle xcex8 relative to the original line OC, the circularity deviation calculating device further obtains the output xe2x80x9cyxe2x80x9d measured by the first measuring device at the each measuring point xe2x80x9cpxe2x80x9d in the form of a function y(xcex8) of the angle xcex8, by utilizing a first variable-transformation for transforming the relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86 obtained when the output xe2x80x9cyxe2x80x9d is measured by the first measuring device at the each measuring point xe2x80x9cpxe2x80x9d, into the angle xcex8.
(9) The apparatus according to the above mode (8), wherein the first variable-transformation is a variable-transformation xe2x80x9cxcex8=f (xcfx86, x, xcex9)xe2x80x9d for transforming the relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86 obtained when the output xe2x80x9cyxe2x80x9d is measured by the first measuring device at the each measuring point xe2x80x9cpxe2x80x9d, into the angle xcex8, by utilizing a predetermined group of parameters A for defining an attitude of the motion controlling mechanism.
(10) The apparatus according to the above mode (9), wherein the predetermined group of parameters xcex9 includes at least one of a length of at least one of a plurality of constituents of the motion controlling mechanism, and a magnitude of at least one of angles each of which is formed between ones of the plurality of constituents adjacent to each other.
(11) The apparatus according to the above mode (9) or (10), wherein the motion controlling mechanism comprises:
a first arm coupled with an stationary member, pivotable about a first pivoting axis offset in parallel from the rotation axis;
a second arm coupled with a free end of the first arm, pivotable about a second pivoting axis offset in parallel from the rotation axis, the second arm configured to have a first sub-arm extending from the second pivoting axis; and a second sub-arm secured to the first sub-arm so as to form a predetermined fixed angle xcex6 therebetween, the second sub-arm carrying at a free end thereof the first measuring device, the predetermined group of parameters xcex9 includes at least one of a deviation xe2x80x9cDxe2x80x9d of the first pivoting axis from a reference axis of the stationary member in a horizontal direction; a height xe2x80x9cHxe2x80x9d of the first pivoting axis from the reference line; a radius xe2x80x9cRxe2x80x9d of a circular locus followed by the center of the cylinder during rotation thereof about the rotation axis; a length xe2x80x9cL1xe2x80x9d of the first arm; a length xe2x80x9cL21xe2x80x9d of the first sub-arm; a length xe2x80x9cL22xe2x80x9d of the second sub-arm; and the predetermined fixed angle xcex6.
(12) The apparatus according to the above mode (11), wherein the object is a workpiece, a circumferential surface of which is to be machined by a machine, the machine is a cylindrical grinding machine grinding the circumferential surface of the workpiece by holding a tool attached to a tool stand of the cylindrical grinding machine, in contact with the circumferential surface of the cylinder, while rotating the tool about the rotation axis xe2x80x9cWxe2x80x9d, the tool stand functioning as the stationary member, the rotation axis xe2x80x9cWxe2x80x9d functioning as the reference axis of the stationary member.
(13) The apparatus according to any one of the above modes (8)-(12), wherein the circularity deviation calculating device further comprises:
distance obtaining means obtaining from the function y(xcex8), by utilizing a technique for analysis such as a harmonic analysis the distance xe2x80x9crxe2x80x9d from the original point O, of the each measuring point xe2x80x9cpxe2x80x9d on the circumferential surface of the cylinder, in the form of a function r(xcex8) of the angle xcex8;
second variable-transforming means transforming the function r(xcex8) into a function r(xcfx86) of the rotating angle xcfx86, using a second variable-transformation for transforming the angle xcex8 and relative position xe2x80x9cxxe2x80x9d obtained at the each measuring point xe2x80x9cpxe2x80x9d into the rotating angle xcfx86; and
compensatory amount obtaining means obtaining an amount xcex4x by which the relative position xe2x80x9cxxe2x80x9d is to be compensated for permitting the function r(xcfx86) to become closer to a target radius am of the cylinder as a result of machining of the circumferential surface of the cylinder, in the form of a function xcex4x(xcfx86) of the rotating angle xcfx86.
(14) The apparatus according to the above mode (13), wherein the second variable-transformation is regarded as an inverse-transformation of the first variable-transformation in terms of a relationship between the rotating angle xcfx86 and angle xcex8.
(15) The apparatus according to any one of the above modes (1)-(14), wherein the first measuring device includes a plurality of measuring members, each measuring member intended to be in contact with the circumferential surface of the cylinder on two contact surfaces of the each measuring member, the two contact surfaces of the each measuring member being opposed to each other with an opposing angle xcex1 therebetween, which angle xcex1 is unequal to 180 degrees and which is different from opposing angles xcex1 of other ones of the plurality of measuring members.
(16) The apparatus according to the above mode (15), wherein the plurality of measuring members are arranged in a common plane bisecting the opposing angles xcex1 of the plurality of measuring members, the first measuring device further includes a sensor to be used commonly with the plurality of measuring members, which sensor measures the cylinder in one measuring direction on the common plane.
(17) The apparatus according to any one of the above modes (1)-(16), wherein the first measuring device includes a plurality of sensors each measuring the cylinder, such that the plurality of sensors are arranged at different phase angles 73  about an original point O defined to be located at or near a center of the circumference of the cylinder.
(18) The apparatus according to the above mode (17), wherein at least one of the plurality of sensors includes an adjusting mechanism permitting a position or an orientation of the measuring direction of the at least one sensor, to be changed on the basis of an average radius a0 of the cylinder, thereby enabling an adjustment in a position of a point of intersection of a plurality of lines extending from the respective sensors in the corresponding measuring directions.
(19) The apparatus according to any one of the above modes (1)-(18), further comprising:
a motion sensor detecting a motion parameter "xgr" related to a mechanical motion of the motion controlling mechanism; and
parameter correcting means correcting at least one of constants belonging to the predetermined group of parameters xcex9, which constant is necessary to be considered for replacement, repair or adjustment of the first measuring device, the correction being effected on the basis of a target radius am of the cylinder, and the motion parameter "xgr" detected by the motion sensor in a state where a gauge cylinder is contacted with the first measuring device, an actual radius of the gauge cylinder not being eccentric with the rotation axis, which actual radius is equal to the target radius am.
(20) The apparatus according to any one of the above modes (1)-(19), further comprising:
a motion sensor detecting a motion parameter "xgr" related to a mechanical motion of the motion controlling mechanism; and
original point position measuring means measuring a position of an original point O defined to be fixedly located at or near a center of the cylinder, which position is defined relative to the rotation axis, on the basis of the relative position xe2x80x9cxxe2x80x9d or a value related thereto, the rotating angle xcfx86 or a value related thereto, and the motion parameter "xgr" or a value related thereto.
In the apparatus according to this mode (20), the use of a motion parameter "xgr" related to a mechanical motion of the motion controlling mechanism enables a more accurate detection (i.e., measurement) of coordinates of a center (i.e., a position of an axis of an eccentric cylinder) of an eccentric cylinder such as a crankpin.
(21) The apparatus according to the above mode (20), wherein the motion sensor includes at least one of a pivoting angle sensor detecting a pivoting angle of an arm of the motion controlling mechanism, which arm functions to produce the mechanical motion of the motion controlling mechanism by a pivoting motion of the arm, and an arm length sensor detecting a length of the arm.
(22) A cylindrical grinding machine comprising:
an apparatus for measuring a circularity deviation defined in any one of the above modes (1)-(21);
a grinding device grinding a cylinder defined in the above mode (1), by holding a tool attached to a tool stand of the cylindrical grinding machine, in contact with a circumferential surface of the cylinder, while rotating the tool about a rotation axis xe2x80x9cWxe2x80x9d; and
synchronization controlling means synchronously controlling a relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86 defined in claim 1, during operation of the grinding device, and controlling the synchronization of the relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86, on the basis of a result produced by operation of the apparatus for measuring the circularity deviation.
The apparatus according to this mode (22) would achieve the second object of the present invention, which is to say, to provide an apparatus for machining an eccentric cylinder having eccentricity as intended or not, with an improved circularity of the eccentric cylinder and in a reduced time.
The present apparatus may be used such that an accurate measurement of the circularity deviation of the eccentric cylinder of a workpiece, and an accurate machining process of the workpiece are performed without removal of the workpiece from a machine for machining the workpiece.
(23) A apparatus for measuring a center position of a cylinder of an object intended to be integrally rotated about a rotation axis, the cylinder being eccentric as either intended or not with the rotation axis, the apparatus comprising:
a contact member intended to be in contact with a circumferential surface of the cylinder;
a motion controlling mechanism permitting the contact member to be moved in a circumferential direction of the cylinder in contact with the circumferential surface of the cylinder, during rotation of the cylinder about the rotation axis;
a motion sensor detecting a motion parameter "xgr" related to a mechanical motion of the motion controlling mechanism; and
original point position calculating device calculating a position of an original point O defined to be fixedly located at or near a center of a circumference of the cylinder, as the center position of the cylinder, which position is defined relative to the rotation axis, the calculation being effected on the basis of a relative position xe2x80x9cxxe2x80x9d of the rotation axis relative to the apparatus for measuring the center position of the cylinder or a value related thereto, a rotating angle xcfx86 of the cylinder about the rotation axis or a value related thereto, and the motion parameter "xgr" or a value related thereto.
In the apparatus according to this mode (23), the use of a motion parameter "xgr" related to a mechanical motion of the motion controlling mechanism enables a more accurate detection (i.e., measurement) of coordinates of a center (i.e., a position of an axis of an eccentric cylinder) of an eccentric cylinder such as a crankpin.
Thus, the apparatus according to this mode (23) would achieve the third object of the present invention, which is to say, to provide an apparatus for accurately and quickly measuring a position of a center of an eccentric cylinder having eccentricity as intended or not.
(24) The apparatus according to the above mode (23), wherein the object is a workpiece, a circumferential surface of which is machined by a machine holding a tool attached to a tool stand of the machine, in contact with the circumferential surface of the workpiece for machining, the measurement of the center position by the apparatus for measuring the center position is performed without removal of the workpiece from the machine.
(25) The apparatus according to the above mode (24), wherein the machine moves the cylinder and the tool stand relatively to each other in a feeding direction perpendicular to the rotation axis, thereby permitting the tool to follow the cylinder during rotation of the cylinder about the rotation axis, resulting in a change in the relative position xe2x80x9cxxe2x80x9d.
(26) The apparatus according to any one of the above modes (23)-(25), wherein the original point position calculating device comprises:
a measuring device measuring the relative position xe2x80x9cxxe2x80x9d;
a measuring device measuring the rotating angle xcfx86; and
original point position calculating means calculating the position of the original point O, on the basis of the measured relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86, and the motion parameter "xgr" detected by the motion sensor.
(27) The apparatus according to any one of the above modes (23)-(26), wherein the motion sensor includes at least one of a pivoting angle sensor detecting a pivoting angle of an arm of the motion controlling mechanism, which arm functions to produce the mechanical motion of the motion controlling mechanism by a pivoting motion of the arm, and an arm length sensor detecting a length of the arm.
(28) The apparatus according to any one of the above modes (23)-(27), wherein the original point position calculating device obtains a phase angle error xcex94xcfx86 defined as a deviation of an actual value from an ideal value of the rotating angle xcfx86, performs correction using the obtained phase angle error xcex94xcfx86 for the actual value of the rotating angle xcfx86, and obtains an amount xe2x80x9cRxe2x80x9d by which the original point O is offset from the rotation axis, by means of measurement or calculation, thereby performing measurement or correction of the position of the original point O relative to the rotation axis.
(29) The apparatus according to any one of the above modes (23)-(28), further comprising parameter correcting means correcting at least one of constants belonging to a predetermined group of parameters xcex9 defining an attitude of the motion controlling mechanism, which constant is necessary to be considered for replacement, repair or adjustment of the first measuring device, the correction being effected on the basis of a target radius am of the cylinder, and the motion parameter "xgr" detected by the motion sensor in a state where a gauge cylinder is contacted with the contact member, an actual radius of the gauge cylinder not being eccentric with the rotation axis, which actual radius is equal to the target radius am.
(30) The apparatus according to any one of the above modes (23)-(29), further comprising an apparatus for measuring a circularity deviation defined in any one of the above modes (1)-(22).
(31) A cylindrical grinding machine comprising:
an apparatus for measuring a center position defined in any one of the above modes (23)-(29);
a grinding device grinding a cylinder defined in the above mode (23) by holding a tool attached to a tool stand of the cylindrical grinding machine, in contact with a circumferential surface of the cylinder, while rotating the tool about a rotation axis xe2x80x9cWxe2x80x9d; and
synchronization controlling means synchronously controlling a relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86 defined in the above mode (23) during operation of the grinding device, and controlling the synchronization of the relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86, on the basis of a result produced by operation of the apparatus for measuring the center position.
The apparatus according to this mode (31) would achieve the fourth object of the present invention, which is to say, to provide an apparatus for machining an eccentric cylinder having eccentricity as intended or not, with an improved accuracy of a position of a center of the eccentric cylinder and in a reduced time.
In addition, the apparatus according to this mode (31) would enable manufacture of an eccentric cylinder with an accurate eccentricity thereof relative to the rotation axis and an accurate phase thereof about the rotation axis.
The result to be provided by the apparatus according to this mode (31) will be described by way of an example in which a crankpin of a crankshaft used in an engine having a plurality of cylinders. In this example, each crankpin can be manufactured such that each crankpin is extremely accurate in position. Therefore, events such as an equalization of compression ratios of a gas to be ignited among the plurality of cylinders, and optimization of an ignition timing for each cylinder can be performed with an extremely high degree of accuracy, with the result that engines can be manufactured so as to have such a high performance that fuel consumption, noise, vibration, and otherwise are well restricted.
(32) A cylindrical grinding machine comprising:
an apparatus for measuring a circularity deviation defined in any one of the above modes (1)-(22);
an apparatus for measuring a center position defined in any one of the above modes (23)-(29);
a grinding device grinding a cylinder defined in the above mode (1) or (23), by holding a tool attached to a tool stand of the cylindrical grinding machine, in contact with a circumferential surface of the cylinder, while rotating the tool about a rotation axis xe2x80x9cWxe2x80x9d; and
synchronization controlling means synchronously controlling a relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86 defined in the above mode (1) or (23), during operation of the grinding device, and controlling the synchronization of the relative position xe2x80x9cxxe2x80x9d and rotating angle xcfx86, on the basis of results produced by operation of the apparatus for measuring the circularity deviation and the apparatus for measuring the center position.
The apparatus according to this mode (32) would achieve the fifth object of the present invention, which is to say, to provide an apparatus for machining an eccentric cylinder having eccentricity as intended or not, with an improved circularity of the eccentric cylinder and an improved accuracy of a position of a center of the eccentric cylinder, and in a reduced time.
(33) The apparatus according to the above mode (32), wherein a non-exclusive combination of the measurement or correction of the position of the original point calculated by the original point position calculating device, the calculation of the circularity deviation by the circularity deviation calculation device, and the operation of the synchronization controlling means is effected sequentially a required number of times, thereby permitting a profile of a cross section of the cylinder to gradually approach a geometrically true circle.